When are thank you cards appropriate and should they be demanded?

I know I probably won’t look great in this post, but I need some etiquette help.

In November, my SIL gave us a gender reveal party. All I asked for was to send her the envelope and she get a cake. I even offered to pay for it. She ended up throwing a huge party and it was like a mini baby shower. It was honestly, a little annoying because we got a ton of clothes, and most were super cute, but impractical poofy dresses. We thanked her kindly for the party over and over again. During our visit, there was a huge blow up where she went crazy on us and we haven’t spoken since.

It came out after the fact, that my MIL and FIL had helped with the cost of the party and gifts. Not sure how much or what specifically. We thanked them profusely as well.

I had an actual baby shower that my MIL and FIL did not send a gift to. They said they felt the gender reveal was their gift. Obviously we are grateful for what they did, but we kind of hoped they would get us something useful off the registry, in addition to what they had already given us (whatever that was exactly).

I sent out thank you cards for my baby shower gifts. I didn’t even think to send one to them for the gender reveal. Upon our baby’s birth, my MIL and FIL visited. They flat out asked me where their thank you card was. I explained my perspective honestly...that I didn’t think to send a card for the reveal, as we hadn’t expected gifts, nor were we aware of what they actually contributed. I also mentioned that although we were grateful, we were a little sad they hadn’t offered a smaller gift from our registry, as that would have been more helpful to us.

For weeks I have been asking my significant other what to put in a thank you card to them. He thinks we shouldn’t send one. I feel awkward because they asked. I have no idea what to say without making it sound inauthentic. Today I received this text, from my MIL.

What do I do? What do I say in the card? Am I a horrible person?

I know this probably makes us sound ungrateful, but it just kind stunk getting a party we didn’t ask for and then being told to appreciate it when we were still lacking baby essentials from our registry.

I know I will get a lot of flack for “expecting” a shower gift. Obviously no one ever has to give someone a gift, and we can’t control what people get us. It’s the thought that counts. I think it’s situational with this family though. Maybe we are a little jealous? His father gives hundreds a month to his sister and helps support their child through money, gifts, and private school tuition. So I guess we kind of just thought we might get some diapers at least? 🤷🏼‍♀️

And as petty as we sound, at what point is it inappropriate to demand a thank you card? Just assume we are rude and move on.

What are your thoughts? I feel like both sides could have made better decisions.

Edit: While they were here I offered to write a card out for them, and said I was sorry they felt neglected. They told me I had to mail it.

Edit: I did send a thank you card. I wrote one yesterday, despite it being awkward and vague. And in a week I might send a text asking for a thank you card for my thank you card.

Edit: Their contribution to the party wasn’t overly sincere, given my SIL simply overspent and asked them for money. Yes, the contributed. It was acknowledged and they were thanked over and over. So to demand a sincere thank you for an insincere gift is a little off to me.

**Yes, I know I sound ungrateful. I should have kept my disappointment to myself, in hindsight. Some feelings, although valid, need not be expressed. My SO was most upset about not receiving a shower gift. I was mostly expressing his disappointment, though I was surprised they did not send a gift as well. I felt it only fair to provide all the details, even if it makes me look bad, since I was asking for advice. However, I did not ask to be ridiculed and gave my character attacked. You do not know me, so please don’t try to decide who I am.**